Technical Abstract:
Determining how fungal peptides induce plant responses may further our understanding of the disease resistance mechanisms protecting agricultural crops, and the factors influencing the susceptibility of weed species to potential bio herbicidal agents occurring naturally in the environment. A 24-kDa peptide isolated from culture filtrates of Fusarium oxysporum, Nep1, elicits physiological responses in a broad range of plant species. Nep1 induces necrosis in a variety of weed species within 48 hours of foliar spray treatment. Dandelions (Taraxacum officionale Weber) and spotted knapweed (Centaurea maculosa Lam.) show extensive necrosis following treatment, and are being used to assess weed responses to the peptide. We are isolating RNA from treated and control plants and using differential display (DDRT-PCR) to identify genes that are differentially expressed in response to Nep1 treatment. Initial screening will focus on plant genes that are up regulated or down regulated within four hours of treatment with the necrosis-inducing peptide. More than 200 bands of interest have been isolated from differential display gels and will be confirmed based on replicate display profiles and Northern blots prior to cloning and sequencing. Parallel studies with Arabidopsis thaliana L., which also develops extensive necrosis following Nep1 application, may facilitate tentative identification of genes of interest based on sequence homology.